It is known to provide vehicle suspension systems with adjustable suspension units. A suspension controller can control the height of the suspension units to provide a self-levelling function whereby the height of each suspension unit is maintained at a target height. The suspension control unit will typically seek to increase the suspension height if it is lower than the target height; and decrease the suspension height if it is higher than the target height.
A suspension system for a motor vehicle is known from EP 0900152 to make vehicle hang-ups less likely. The suspension system is operative to adjust the ride height between sprung and unsprung parts of the vehicle. A height sensor is provided for air springs within the suspension to measure height changes. An electronic control unit maintains the ride height at each air spring within predetermined limits. The electronic control unit inhibits ride height changes when the vehicle is stationary to avoid height changes to compensate for loading/unloading or vehicle maintenance.
A bimodal suspension for an amphibious vehicle is known from GB 2402106. The wheels of the vehicle are raised when a wheel height detector detects wheel droop. As a safety check, a sensor detects that the vehicle is in water.
At least in certain embodiments the present invention sets out to overcome or ameliorate shortcomings associated with prior art suspension systems.